It is unavoidable that humans emanate odors. The odors may originate from numerous sources including natural bodily secretions such as perspiration and oils. In addition, a person's clothing may absorb odors and subsequently release them to the surrounding environment. Numerous cosmetic and health care products have been developed to mask unpleasant odors. Colognes, perfumes, scented soaps, deodorants and the like, which are employed for such purposes, mask an undesirable odor by replacing it with another odor that is considered more pleasing.
In certain situations, however, it is desirable to provide an odorless or scentless presence. For example, persons such as hunters, naturalists, wildlife photographers, and wildlife biologists must have the ability to approach wildlife animals in close proximity. Wildlife animals have a keenly developed sense of smell that can readily distinguish odors that are not indigenous to their natural habitat. Such odors may include those emanating from humans who attempt to gain close proximity to the animals. Perfumes, scented soaps, and colognes may mask odors but are themselves readily detected by the animals. Thus, there is a need for a means adapted to readily, efficiently, and effectively trap human odors such that a user presents a virtually odorless or scentless appearance, thereby enabling one to approach wildlife animals in close proximity.
Clothing articles have been designed to prevent detection of a wearer's odors by wildlife animals. Such clothing designs include deodorizing agents incorporated into one or more layers of fabric, for example, the designs disclosed in U.S. Pat. Nos. 5,383,236 and 5,539,930. Deodorizing agents that have been used in such fabrics include activated charcoal, chlorophyll, baking soda, activated alumina, soda lime, zeolite, calcium oxide, and potassium permanganate. Naturally occurring odors emanating from a wearer are trapped by such deodorizing agent(s).
Various kinds of deodorant particles are used as deodorizing agents. Activated carbon is a widely used agent which is capable of trapping a broad spectrum of odor-causing compounds. Activated carbon, often used in the form of activated charcoal, functions to deodorize by adsorbing odors. Odor adsorption by activated carbon occurs by increasing the surface porosity of the fabric and allowing odor-causing compounds to become physically attached to the fabric. Other physically adsorbing particles include zeolite and impregnated carbon. A disadvantage of using physically adsorbing particles to control odors is that the particles lose odor trapping effectiveness when they becomes moist, such as a hunter might experience in the field from perspiration and/or the environment. Moreover, odor-trapping particles that are physically attached to fabric can be loosened from the fabric during washing, further decreasing the availability of active agent in subsequent uses of the fabric. Furthermore, these agents can be harmful to fabrics and therefore are not preferred as an odor controlling agent for fabrics. For example, activated charcoal easily stains light colored fabrics, and zeolites are seen as a light colored stain on dark colored fabrics. Also, zeolites can cause a “harsh” feel if too much is deposited onto a fabric.
Other deodorant particles are classified into acidic or alkaline particles depending on the charge of the odoriferous material the particle can neutralize. Acidic deodorant particles, which can neutralize acidic odors, include, for example, potassium carbonate, potassium hydrogencarbonate, sodium carbonate, sodium hydrogencarbonate, ethanolamine, hexamethylenediamine, and piperazine. Alkaline deodorant particles, which can neutralize alkaline odors, include, for example, phosphoric acid, sulfuric acid, nitric acid, malic acid, citric acid, and ascorbic acid. A disadvantage of using both acidic and alkaline particles in the same fabric is that when particles have different charge states are adjacent, odoriferous materials may be leached from one deodorizing particle to another, thereby decreasing the overall deodorizing performance, as suggested by European Patent No. 0882485 B1. Therefore, it would be advantageous for a single deodorizing agent to neutralize odoriferous materials without regard to the ionic charge of the materials.
Other methods of odor control utilize agents, or “actives,” that are targeted to react with odors having specific chemical functional groups. Examples of such actives are biguanide polymers, which complex with organic compounds containing organically bound nitrogen and/or sulfur atoms and fatty alcohol esters of methyl methacrylic acid which react with thiols, amines, and aldehydes. Such actives are limited in the scope of protection which they afford because they only react with limited types of odors.
Deodorant particles can be attached to fabric using various conventional means. For example, yarn and fabric can be treated with deodorizing agents by physically incorporating solid particles, such as activated carbon, into the yarn using a padding technique or an air dispersion technique. A disadvantage of physically attaching deodorant particles to a fabric is that the particles may not be uniformly distributed in the fabric.
Other methods involve using a binding agent to attach solid deodorizing particles to yarn. In one such technique, an aggregator resin is first attached to a fabric, and the particles are then aggregated onto the resin. In another means of attaching a deodorizing particle to a fabric, a fine grain mineral powder is attached to a fiber substrate with the adhesive effect of an aqueous dialdehyde starch. (See Japanese Patent Application No. 07067949 JP.) A disadvantage of using such binder materials to attach deodorant particles to a fabric is that the surfaces of the deodorant particles can be covered with the binder, which inhibits any deodorizing performance of the particles.
Other conventional methods for attaching deodorizing agents to yarns and fabrics employ chemically bonding the agents to the substrate. For example, Japanese Patent Application No. 01254274JP discloses chemically reacting various deodorizing agents, including polymers such as a vinylic polymer, a polyamino acid, an amino-modified silicone resin, and a hydroxylated ethyleneurea to a fiber product. In another example, U.S. Pat. No. 4,675,014 discloses a sanitary hygiene aid employing an absorbent material of cellulose fibers incorporating anionic salt-forming moieties through a process of esterification or etherification. Copper, used as a deodorizing agent, is chemically attached to the fibers through those anionic moieties, and is resistant to being washed out.
A relatively recent and widely used agent for odor control is cyclodextrin. Cyclodextrins are ring-shaped sugar molecules with a hydrophilic surface and an empty hydrophobic cavity. Cyclodextrins can form complexes with many guest molecules. Guest molecules are taken up, or encapsulated, by the chemical structure of cyclodextrins. As such, cyclodextrins have been added to materials for various purposes, including use as odor-encapsulating agents and to complex with and release actives such as antimicrobials and fragrances. For example, U.S. Pat. Nos. 5,783,552 and 5,660,845 disclose uncomplexed cyclodextrins incorporated into an article for trapping odors in the form of particles and powders, or releasably attached to a substrate.
A method of immobilizing uncomplexed and complexed cyclodextrins to cellulose fibers using a cross-linking means that covalently bonds the cyclodextrin to a substrate has been disclosed. Such a cross-linking means includes, for example, polymeric anionic reactive compounds having repeating units containing two or more anionic functional groups, such as carboxylic acids, anhydride groups, or the salts thereof. The cross-linking agent is disclosed as being capable of forming ester or hemiacetal bonds with hydroxyl groups on the polysaccharide of the substrate and with the cyclodextrin. This method is disclosed in PCT Application Publication No. WO 0148025, which is incorporated herein by reference in its entirety. A disadvantage of attaching cyclodextrin to cellulose in a fabric in this manner is that such chemical bonds are susceptible of being solubilized during washing of the fabric.
Other methods of attaching deodorizing agents have been found to increase resistance of attached particles to being washed away. As an example, Japanese Patent Application No. 11293559JP discloses that in an antimicrobial deodorant nylon fiber article, wash resistance is increased when silver-bearing titanium oxide microparticles are adsorbed onto the nylon fibers. Japanese Patent Application No. 09087955JP discloses securing deodorizing agents to a fabric by integrally forming the deodorizing agent with the fabric. In this approach, a thermoplastic polymer is blended with a deodorizing inorganic compound, the blend is melted, the molten mixture is extruded, continuous fibers are formed from the extrusion, and the fibers are collected on a substrate to form a web. Such approaches to improving wash resistance of an anti-odor agent on a fabric add additional steps, tend to be expensive, and are thus disadvantageous. Moreover, such methods have not been disclosed for improving cyclodextrin wash resistance.
Cyclodextrins can be treated with reactive moieties, or derivitized, to form derivatives that can in turn react with a fabric or other substrate. For example, cyclodextrin can be reacted with epicholohydrin and chlorinated or fluorinated triazinyl compounds, which can subsequently react with cellulose. These methods typically require pretreatment of the cyclodextrin before it can be combined with cellulose, and also suffer from safety, environmental, and high reactivity issues associated with the halogenated reactants. Accordingly, there is a need for improved methods of immobilizing cyclodextrin to cellulose in textiles that improve wash resistance and that are useful for making articles of clothing.
In addition, cyclodextrin particles and powders may shift away from the preferred location of an article, for example, in the underarm portion of a garment where the article is likely to be impinged by an odor, and move to areas where they are less effective for their intended purpose. This problem was addressed in U.S. Pat. No. 5,733,272 by the use of an “adhesive,” such as polyethylene glycol to attach the cyclodextrin to particular areas of an article. However, immobilization of cyclodextrin using adhesives decreases the “hand,” or feel, of the fabric as well as other characteristics desirable of fabric used in making clothing articles.
Imidazolidone has been used in textile finishing processes. For example, U.K. Patent No. 864,432 discloses reacting formaldehyde with heated urea and imidazolidone to permit a resin finish having a more linear molecular structure. The introduction of the linear structure of the urea/imidazolidone/formaldehyde finish more effectively maintains the flexibility and tensile strength of the textile than that produced by formaldehyde alone. In another conventional process, U.S. Pat. No. 3,652,583 discloses an ester exchange reaction of an imidazolidone compound and a water-soluble polyalkylene glycol to treat textile materials in order to increase hydrophilic, soil releasing, and resoiling resistance properties of the material.
Conventional techniques for preparing cellulose-containing materials have employed cross-linking with imidazolidone. For example, one method for obtaining resilient, bulking fibers useful for absorbent fabric structures in towels, diapers, medical dressings, and the like, involves cross-linking cellulose molecules in the fibers using a mixture of glyoxal and imidazolidone. U.S. Pat. No. 5,366,591 discloses such a process, in which the cross-linking agents are capable of combining with at least two hydroxyl groups of cellulose molecules. However, imidazolidone has not been advantageously utilized to provide strong ether bonds to cross-link odor-encapsulating cyclodextrin with cellulose in fabric.
Thus, there is a need to provide a process for chemically bonding an odor-encapsulating agent to textiles that provides a strong bond between the agent and the fabric to increase wash resistance and thereby provide more durable odor-encapsulating activity to the fabric. There is a need for such a process that bonds an odor-encapsulating agent to textiles in a more uniform manner, thereby enhancing the odor-encapsualting effectiveness of the treated fabric. There is a need for such a process that accomplishes such strong chemical bonding of an odor-encapsualting agent to a textile material in a single-step process without the need to first form derivatives of the agent. There is a need for such a process that chemically bonds a broad spectrum odor-encapsualting agent such as cyclodextrin to cellulose in a textile.